This invention relates to the testing of construction surfaces such as horizontal concrete slabs and roadways or vertical building walls and columns.
The detection of irregularities in test surfaces by relatively massive mobile apparatus is already well known as disclosed, for example, in U.S. Pat. Nos. 3,266,302, 3,453,877 and 3,470,739. According to U.S. Pat. No. 3,266,302, irregularities are detected by displacement of a potentiometer wiper mounted on a wheeled vehicle frame. According to U.S. Pat. No. 3,470,739, a feeler rod projecting from a measuring unit engages the test surface as the unit is guided for movement along a path parallel to a reference surface. Electrical calculating circuits are utilized to measure displacement of the wiper or feeler rod according to the latter two patents. A mechanical measuring system is utilized according to U.S. Pat. No. 3,453,877. Rather complex measuring arrangements are featured in the foregoing patents, subject to many sources of error and relatively costly to produce.
It is therefore an important object of the present invention to provide a relatively simple, versatile and less massive tool for detecting irregularities in a test surface.